London, Dec 30 (IANS): The father of Greta Thunberg, the 16-year-old Swedish environment activist, has said that she "changed" and has become "very happy" as a result of her activism that has contributed towards a global movement demanding world leaders to take action over climate change.

In an interview with the BBC, Svante Thunberg said: "You think she's not ordinary now because she's special, and she's very famous, and all these things. But to me she's now an ordinary child - she can do all the things like other people can.

"She dances around, she laughs a lot, we have a lot of fun - and she's in a very good place."

Speaking to the BBC, Svante Thunberg said that his daughter had struggled with depression for "three or four years" before she began her school strike.

"She stopped talking... she stopped going to school," he said, adding that it was the "ultimate nightmare for a parent" when Greta began refusing to eat.

To help her get better, Svante Thunberg spent more time with Greta and her younger sister, Beata, at their home in Sweden. Greta's mother, opera singer and former Eurovision Song Contest participant Malena Ernman, cancelled contracts so the whole family could be together.

Over the next few years they began discussing and researching climate change, with Greta becoming increasingly passionate about tackling the issue.

Svante Thunberg has accompanied Greta on her sailing expeditions to the UN climate summits in New York and Madrid. She refuses to travel by air because of its environmental impact.

"I did all these things, I knew they were the right thing to do... but I didn't do it to save the climate, I did it to save my child," he told the BBC.

Greta was nominated for this year's Nobel Peace Prize, after spearheading the global movement, which also led to co-ordinated school strikes across the globe.

Earlier this year, she was named the TIME magazine's 2019 Person of the Year.